Although body channel obstructions such as blocked arteries have been treated heretofore using surgical arteriotomy techniques as well as with medicines for dissolving certain obstructive substances, a substantial effort has been made to perfect so-called minimally invasive techniques using catheter-based systems. In such systems, the artery is entered at a site remote from the obstruction so that elongated devices can be guided through the arterial system to the desired site. Such devices have included a catheter with a tapered tip which was pushed through the area of obstruction using a so-called Dotter technique or a catheter with an inflatable balloon near its distal tip for using the balloon angioplasty technique.
Other mechanical means of opening arteries include the use of rapidly rotating elements, for example the "Auth" technique which is an elongated device with a rotating diamond studded tip which grinds the obstructing material as it advances within the artery, or the "Fischell" technique which slices the blockage as it is withdrawn from the artery, or the "Stack" or Kensey techniques "Simpson" which use elongated catheters with rotating blades to chop the obstructing material, or the "Simpson" which is an elongated catheter that slices the obstruction at the side of the distal tip of the device.
Thermal and laser energy have also been used to open obstructed arteries. The "hot tip" technique utilizes thermal energy generated by electrical, chemical or laser to heat the tip of an elongated catheter which then vaporizes or melts the area of obstruction as it is advanced through the artery. Direct laser energy can be transmitted through elongated fiberoptic catheters to the site of obstruction in order to vaporize the obstruction.
To date, the mechanical means of removing obstructions from arteries are associated with formation of debris which flows downstream and blocks more distal vessels or with high frequency of closure of the artery after the procedure ranging from 25% to 50% in the case of the Auth, Simpson, balloon angioplasty, and related techniques. The cause of the reclosure is thought to be related to the mechanical damage to underlying healthy tissue and to the internal surface characteristics produced by the mechanical procedures. Attempts have been made to use laser energy or thermal energy after the mechanical techniques to improve the damaged surface characteristics and to weld any defects in the artery wall caused by the initial mechanical procedures.
Attempts have also been made to combine the use of laser energy with an angioplasty catheter to remove arterial obstructions as disclosed by Leckrone in U.S. Pat. Nos. 4,685,458 and 4,747,405. In these patents, a catheter having an attached inflatable balloon is provided with laser transmission filaments for ablating or dissolving obstructive material in an arterial passage.
One object of the present invention is to provide an improved catheter device for treating obstructions or blockages in body channels which combines the use of mechanical force thereof for displacing or compressing blockage material and manipulations with laser energy for dissolving or severing the blockage material.
Another object of the invention is to provide a catheter device for removing obstructions in body channels that enables the use of a reduced amount of laser energy directed so as to sever rather than dissolve the obstructing material, thereby reducing the danger of damaging healthy bodily tissue.
Another object of the invention is to provide a catheter device for removing obstructions in body channels that enables particles of removed obstructive material in body channels such as arteries to be trapped and retrieved, rather than allowed to fall into the fluid stream of the body channel.
Yet another object of the invention is to provide a catheter device for removing obstructions in body channels that is readily controllable and maneuverable in use to provide for efficient removal of body channel obstructions without damage to healthy tissue and thus with minimum risk to the patient.